This research program is concerned with the interaction of genetic and experiential factors that affect the development of behavior. Experiential factors are manipulated by systematically exposing new born mice to various treatments such as environmental enrichment, early food deprivation, cold stress, and aperiodic electric shocks. Genetic variation is manipulated by using inbred and random bred mouse strains and genetic breeding techniques such as diallel. parent-offspring, and F1, F2 and backcross designs. The dependent measures that are used to assess behavior include open-field emotionality, running wheel activity, exploration, food competition, water consumption, and food hoarding. The main objective of the research program is to discover the dimensions that influence the development of behavior.